This invention relates to apparatus for transversely cutting a web of material to form short lengths thereof, and in particular for cutting up a web to form tickets.
Ticket-cutting machines are known which make use of a rotatable cutting apparatus for forming individual tickets from a web of material carrying repeated printed matter, by transversely cutting the web at intervals corresponding to a dimension of the tickets. Such a cutting apparatus which is arranged at the outlet side of a rotary printer, comprises a pair of infeed elements formed by cylinders or shafts carrying rollers; a rotating cutting device which comprises an upper rotatable cutting cylinder which carries one or more blades, and a lower counter-blade; and means for discharging the cut tickets. All the rotating elements are driven by the main shaft of the machine through transmission means having suitable transmission ratios dependent upon the diameters of the rotary elements, so that the peripheral speeds of all of these elements are the same.
A known cutting apparatus that is used in such a machine comprises an angularly adjustable cutting head which includes an upper frame carrying the rotatable cutting cylinder and the counter-blade, the frame itself being mounted to pivot about a vertical axis which is disposed laterally in relation to the web so as to enable the shaft of the cutting cylinder and the axis of the counter-blade to be disposed at an angle to the web, this angle being variable in dependence upon the rate of feed, that is to say upon the speed at which the web moves. With such a cutting device, this is necessary, since the cutting operation is not carried out along a continuous transverse line in one stroke. Instead, the cut occurs as a series of perforations, these perforations being made one after another by the blades of the cutting cylinder as the cutting cylinder rotates. Thus, the point at which cutting occurs continuously moves along the edge of the counter-blade during rotation of the cutting cylinder. It is, therefore, necessary for the angle of the unit formed by the cutting cylinder and the counter-blade to be adjusted in dependence upon the rate of feed of the web, so as to obtain a straight cut extending at right-angles to the edge of the web.
Hitherto, in such an apparatus having an angularly adjustable cutting head, the driven infeed cylinder has been driven directly from the main shaft of the machine, whereas the cutting cylinder has been driven from the main shaft via a vertical shaft and a pair of bevel pinions which enable the cutting head to pivot about the axis of this vertical shaft.
Although, theoretically, the speeds of rotation of the cutting cylinder and the infeed cylinder of such a cutting apparatus should be matched to produce tickets of constant length, practice has shown that this is not so. In fact, if the ends and edges of stacked tickets, cut up in this manner, are aligned and the tickets are measured, it will be found that the cutting up operation has not been carried out with sufficient precision to enable the tickets to be used in a ticket-issueing machine.
The aim of the invention is to eliminate this disadvantage by particularly simple means which enable tickets to be cut off in an extremely precise manner.